Hammertoe is often defined as a deformity of the toe, where the proximal interphalangeal joint of the second, third, or fourth toe causes the toe to become permanently bent, resembling a hammer. Mallet toe is a similar condition affecting the distal interphalangeal joint. Claw toe is another similar condition, in which the toe is bent in a shape resembling a predator's claw.
These conditions, jointly referred to as deformities of the toe, frequently result from muscle imbalance aggravated by wearing poorly-fit shoes. Such shoes, having excessively high heels or being too short or narrow for the foot, may force the toe into a bent position. Having the toes bent for long periods of time can cause the muscles to shorten, resulting in one of the deformity types mentioned above. This condition is often found in conjunction with bunions, calluses or other foot problems. Toe deformities can also be caused by muscle, nerve, or joint damage, resulting from conditions such as osteoarthritis, rheumatoid arthritis, stroke, Charcot-Marie-Tooth disease or diabetes. In certain age groups, the claw toe is present in every other woman. It can also be found in Friedrich's ataxia and several other neuropathies.
The main problem characterizing these conditions is usually the insufficient length of soft tissues, which constricts the toe, bends the joint, and forms a deformity (commonly a Z-deformity) of the ray. As a result, there is often dorsal prominence of the PIPJ (Proximal Interphalangeal Joint) as well as plantar prominence of the MPJ (Metatarsophalangeal Joint), the proximal phalanx, the distal metatarsal bone and the middle or distal phalanx. Those result in callosities, pain and difficulty in wearing footwear. Hallux Rigidus (also referred to as Hallux Limitus) may develop in the big toe, bringing about pain during the push-off phase of walking, discomfort and increased pressure when wearing footwear.
There are a number of known methods for treating such toe deformities. One method is padding. Different types of shoe orthotics and socks may be used to pad and cover the prominent bones, thus relieving the pressure and reducing the pain, the discomfort and further damage. Another method is based on lengthening of the soft tissues, which is achieved by physiotherapy on early stages, or surgically on late and severe stages. A further method is based on surgical shortening of bones (osteotomy, joint excision, Du Vries procedure etc.).
Many orthotics, such as insoles, are built to function as cushions which relieve the pressure under the metatarsals (metatarsal pad or metatarsal bar). Insoles are usually made of a semi-rigid, non-washable material, while a much less common version is a rigid, washable insole. The rigid ones are said to be less comfortable, and are often made of materials ranging from aluminum to plastics. During walking, the foot moves relatively to the insole, and, therefore the insole has to be custom-made, for example by casting the foot in alabaster or low-temperature thermoplastic polymer. The elevated areas have to include a relatively large surface area to adapt to the foot's motion.
Additionally, some orthotics include separate toe compartments, thus acting like a toe splint, but not to the entire ray. These orthotics do not usually have therapeutic padding under the metatarsal heads, the ray length is not adjustable, and there is a hygiene problem due to sweating of the feet. In specific orthotics which have the upper part of the toe covered by a polymer part, there is risk of callus formation; in the uncovered version, there are no restraints limiting toe bending.
Hallux Rigidus is usually treated with rigid or semi-rigid insoles, that prevent flexion of MPJ (“Morton's extension”), as well as with high shoes containing an anterior rocker. However, this form of treatment limits the patient to one pair of shoes. Another currently accepted method of treating Hallux Rigidus is surgical procedures such as MP1 fusion, MP1 implants and/or Cheilectomy. These procedures are usually expensive, painful and require a post-operative rehabilitation period.
U.S. Pat. No. 4,263,902 to Dieterich discloses an orthopedic sandal for correction of hammer-toes and X-toe (Halux Valgus) being a dual lever arm arrangement pivotable on a horizontal axis transverse to the sole. A pressure element for pressing the toes downward is on one arm and the other arm is fastened to the rearward portion of the foot so that as the food is lifted, the pressure element is pressed downwardly on the hammer-toes.
U.S. Pat. No. 6,093,163 to Chong discloses a unitary device for the correction of hallux valgus, which is made of an elastomeric fabric material that includes a large portion that encloses the forefoot circumferentially, and a smaller portion that encloses the great toe circumferentially. The fabric for constructing the device is cut in such a way that there is a bias towards varus of the great toe. Once the device is applied on the great toe and forefoot, the bias of the cut exerts a varus force on the great toe, thus correcting the valgus deformity.
U.S. Patent Application Publication No. 2008/255490 to Raija discloses a therapeutic device and method for its use. The appliance and method are adapted to realign and straighten the toes of the foot in order to treat the effects of hammertoe, bunions, Morton's neuroma, and the like. Effectively, a harness is placed about the heel of the foot, the harness consisting of a foot strap and heel strap. Sleeves are placed about the particular toes of interest, being as few as one and as many as all of the toes on a foot. Elastic straps are interconnected between the toe sleeves and the foot strap in order to impart a force to the associated toe to straighten and/or realign the toe consistent with correcting a particular malady. The elastic strap may be connected and disconnected by means of hook and loop fasteners at the end of the strap and maintained upon the toe sleeves and foot strap. The positioning of the strap with respect to the toe sleeve and the foot strap effects the direction of the force applied to the toe in accordance with the malady to be treated. Using sleeves may limit usage during rest where no active force is exerted besides the elastic forces within the straps.
The foregoing examples of the related art are intended to be illustrative and not exclusive.